Ap­ple has long bat­tled sug­ges­tions that its tax struc­ture is un­der­hand. But that task may be harder now that a No­bel-win­ning econ­o­mist has called the firm’s Ir­ish tax ar­range­ments “fraud”.

Joseph Stiglitz, a Columbia Univer­sity pro­fes­sor and for­mer World Bank chief econ­o­mist, was talk­ing to Bloomberg TV. He said: “Here we have the largest cor­po­ra­tion in cap­i­tal­i­sa­tion not only in Amer­ica, but in the world… and claim­ing that most of its prof­its orig­i­nate from about a few hun­dred peo­ple work­ing in Ire­land – that’s a fraud”.

Ire­land’s cor­po­ra­tion tax rate of 12.5% is lower than the 35% in the US. How­ever, Ap­ple is thought to be ben­e­fit­ting from a ‘sweet­heart’ deal with the Ir­ish gov­ern­ment that sees it pay­ing just 2%.

The Euro­pean Com­mis­sion is cur­rently in­ves­ti­gat­ing whether such a deal would con­sti­tute il­le­gal state aid – Ap­ple could owe an es­ti­mated $8bn in owed taxes if the com­mis­sion de­cides that’s the case.

How­ever, Tim Cook has said Ap­ple is the largest tax­payer in the world and pays ev­ery cent it owes. He pre­vi­ously de­scribed the US tax code as “aw­ful for Amer­ica” and “made for the in­dus­trial age”.